Optical scanning systems are well known in the art. Reflective, prism, cylindrical drum and X-Y scanners are representative of some of the more important classes of optical scanners. Scanning systems comprising corner mirrors and a scanning mirror are also known. While such devices may satisfy their design criteria, certain limitations have been observed. Some do not instantaneously read out a line, some are subject to radiometric errors such as the cos.sup.4 .theta. fall-off, some operate in either a reflecting or transmitting mode, some will not accept plane targets, some require linear translation, and in others, image fidelity is not optimum.